Oil production method



JunelZ, 1956 R. sPEARow on. PRODUCTION METHQD Filed June 12, 1952INVENToR. Fa/7 pea/"0W BY nr @RNEK United States Patent() OIL PRODUCTIONMETHOD Ralph Spearow, Paola, Kans. i Application June 12, 1952, SerialNo. 293,056

1 Claim. (Cl. 166''4Z) This invention relates to methods for producingoil from oil sands and more particularly to methods for producing onlyoil from sands which normally produce oil contaminated with water.

Many producing oil formations including those requiring repressurizingof some sort often present the problem of water being produced with theoil. This problem is especially serious and aggravated when therepressurizing and oil recovery is by water drive where extra 'water ispumped into the oil sand. Further, when the water drive method has beenused and the maximum recovery achieved thereby, there still remains alarge quantity of oil in the sand together with the added Water which bypresent methods must be recovered together and separation made at thesurface. ln all s'uch cases, lthe primary problem is to handle anddispose of the large quantities of water which are produced with theoil. Another problem requiring much surface equipment is the separationof simultaneously produced oil and water which is in emulsifled form.

Therefore, the primary object of the instant invention is to provide amethod which will produce only oil from oil sands which normally wouldproduce both oil and water.

A further object is to provide a method by which the oil is separatedfrom the water under ground and the water is retained in the sand to aidin maintaining the bottom hole pressure.

Still another object is to provide a method which producesuncontaminated oil from sand normally producing both oil and water thusavoiding the expense and trouble of separating equipment.

Other and further objects of this invention will appear in the followingdescription.

In the accompanying drawing, which forms a part of the instantspecification and is to be read in conjunction therewith, there is shownan embodiment of the invention.

The single figure is a sectional view of an oil well wherein thenecessary casing and tubing for practicing the invention have been set.

In the drawing, the numeral indicates a primary outer casing positionedin the hole bore 11 of an oil well and extending from the ground level12 to the vicinity of the top 13 of an oil sand 14. It should beunderstood that the casing may as well extend into or through theformation with perforations to permit ingress and egress of theformation fluids therethrough. The hole bore 11 is shown in dotted linesextending through the oil sand 14 and at 15, in full lines, is shown theprobable outline of a bottom hole cavern produced by shooting the wellwithout the extension of the casing through the oil sand. The casing 10is cemented to the surrounding formations through which it passes asshown at 16. Although the casing in the drawing terminates at the top ofthe producing sand, it is contemplated that it may be desirable toextend the lower end of the casing into the producing formation ashereinafter explained. A secondary tubing 17 is positioned within thecasing ICE and may extend below the lower end of the casing into the oilsand 14. A discharge valve18 in the tubing above ground level controlsthe flow of iluid through the tubing. A check valve 19'1ocated in thelower end of tubing 17 has ball valve 20 which seats downwardly. Thecasing head 21 furnishes apressure-tight connection 22 between thetubing 17 and the casing 10. Casing 10 is equipped with an inletconnection 23 controlled by valve 24 and an outlet connection 25controlled by valve 26.

In operation, it is assumed that some pressure, natural or artificial,exists on the oil sand thus bringing fluid into the hole bore 1l or shothole 15 where it tends to rise in the casing and tubing. To institutethe method, valve 26 in the casing and valve 18 in the tubing areopened, thus permitting the fluid from the oil sand to rise both in thecasing and tubing to a level according to the pressure existing in thesand. If the bottom hole pressure is great enough, the yfluid may riseall the way to the valves 18 and 26, at which time they would be closed.However, in the drawing only such pressure is assumed as will raise thefluid in the casi-ng and tubing to the level designated by dotted line Aand this level is the top of the oil portion of the uid column whichenters the casing and tubing. Dotted line B designates the interfacebetween the water and oil portions of the column which rises in thecasing and tubing. At this time, the oil and water have no particulartendency toward emulsication but separate naturally according to theirrespective specific gravities, the well fluid not having been subjectedto any mixing turbulence. When the fluid has risen to a level such as isindicated at A in the casing and tubing, the valve 26 and the valve 18are closed. Inlet valve 24 is then opened and pressure is appliedthrough connection 23 to the top of the fluid column in the casing.Sulllcient pressure is imposed to force the fluid column downwardlyuntil the base of the oil portion of the column or interface B islowered to a position below the check valve 19 designated as D. Level Cthen indicates the probable position of the top of the oil portion ofthe column. With the above-mentioned pressure continuously applied,valve 18 in the tubing is then opened. The water and oil containedoriginally in the tubing are rst drained off and then all the availableoil included between levels C and D is likewise withdrawn, As the oilbetween levels C and D is removed, the water level D will rise and it isdesirable to terminate the llow of fluid from the tubing before level Drises to the check valve. When substantially all the available oilbetween these levels has been drained olf through tubing 17, valve 18and valve 24 are closed. Outlet valve 26 is then opened to release thepressure imposed on the fluid column in the casing thereby permittingthe fluid to accumulate again in the casing. As previously suggested, byextending the casing into the producing sand the area of interfacelevels B and D are restricted within the contines of the casing, thuseffectively reducing the area of pressure application, since otherwisethe interface level must be lowered in the entire producing formation.

Repeated cycles of the foregoing operations will reveal the necessarypressure and the time period of application of pressure to the fluidcolumn in the casing to correctly displace the oil portion of the columnto its proper position in relation to check valve 20. Likewise, the timeperiod during which oil is withdrawn from the tubing is determined. Arepetitive cycle of the foregoing operations thereafter is conducted asa continuous process thereby withdrawing measured amounts of oil unmixedwith water from the sand.

A method is thus provided which produces only oil from an oil sand whichnormally would produce both water and oil.

A method has also been provided by which the oil is separated from thewater under ground and the water is retained in the sand to aid inmaintaining the bottom hole pressure.

Furthermore, a method has been provided which produces uncontaminatedoil from a sand normally producing both oil and water-thus avoiding theexpense and trouble of separating equipment.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forthtogether with other advantages which are obvious and which are inherentto the structure.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaim.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

A process for the production of oil from a well producingwater-contaminated fluid, said well having a casing cemented to thesurrounding formations, a pressuretight casing head and a tubingextending through the casing head and within the casing into theproducing horizon with a check valve at the lower extremity of thetubing comprising the steps of opening the casing and tubing at thesurface to cause the fluid to rise in the casing and tubing under theinfluence of the rock pressure in the producing formation and form acolumn in the casing rising to'a height commensurate with the rockpressure, maintaining said column for a period suicient to permitgravitational separation of the water and oil therein, then sealing thecasing and tubing at the surface and imposing pressure 0n the column inthe casing sufcient to drive the water back into the formation and lowerthe interface between the oil and water to a position below the checkvalve in the tubing, unsealing the tubing at the surface to flow oilfrom the tubing and maintaining the tubing unsealed until the interfacerises almost level with the lower end of the tubing, then sealing thetubing and removing the applied pressure on the column in the casing fora period to cause fluid from the formation to rise in the casing andagain form a column of water and oil rising to a height commensuratewith the rock pressure, again maintaining the column for a periodsufficient to cause separation of the oil and water, and repeating inorder and at successive intervals the application of pressure, flowingof oil from the tubing and release of pressure in the casing thereby toestablish a cyclic production operation.

References Cited in the le of this patent UNITED STATES PATENTS1,499,509 Dunn n July 1, 1924 1,499,589 Navin July 1, 1924 1,885,807Doherty Nov. 1, 1932 2,258,614 Kendrick Oct. 14, 1941 OTHER REFERENCESThe Oil Weekly, October 12, 1936, pp. 39, 40, and 42.

